In the manufacture of ready-to-use draperies, drapery sections frequently are formed at a standard width, known as a "five pleat equivalent", which includes five pleats formed along the upper margin of the drapery fabric, with short end runs extending beyond the pleats nearest the fabric edges. Generally, if greater widths are desired, two or more standard sections of the five pleat equivalent width may be stitched together. This particular production technique is, of course, not critical to, nor is it a limitation of, the present invention, but is merely illustrative of typical commercial practice.
Usually, the fabric section is hemmed along the bottom and opposite side edges prior to the pleating operation. The upper edge, along which the pleats are to be formed, is provided with stiffening, typically by the securement along the upper edge extremity of a narrow strip of backram, for example. In preparation for the pleating operation, the buckram is folded against the back surface of the fabric, and the fabric advantageously is turned over the buckram to provide a finished upper edge. Typically, the buckram strip may be of somewhat greater length than the width of the unpleated fabric, in which case the end extremities of the buckram are folded back prior to the folding over of the upper margin of fabric.
The usual operations involved in pleating of the stiffened fabric edge include forming a short "vertical" line of closing stitches adjacent each edge of the fabric (the term "vertical", as used in this context, referring to the orientation in which the drapery fabric normally is to be hung). At various uniformly spaced locations along the stiffened upper margin of the fabric, the fabric is gathered into a short accordion fold pleat, which may be 3-4 inches in height. This is secured by stitching, either in the form of an "L" tack or in the form of an inverted "F" tack, rendering generally permanent the formed pleats.
In the forming of pleats for drapery fabrics and the like, it is known to use a plurality of opposed tucking blades, typically three on the backside of the fabric, opposed by two on the front side. The fabric is first laid over the three blades at the backside, which are spaced apart far enough to receive between adjacent ones, a blade from the opposite side, together with the necessary thicknesses of fabric. While one side, usually the leading side, is held stationary, a single blade from the front side (referred to as a sizing blade) enters between a pair of blades located behind the fabric, penetrating to a predetermined depth and carrying fabric with it to form a first pleat fold. Next, while the first sizing blade retains its position, a second sizing blade enters from the front side, penetrating between and carrying fabric down into the space formed by the next adjacent pair of blades positioned behind the fabric. This forms the second pleat fold. Typically, the sizing blades may be retracted, permitting the formed pleat to be gripped and retained exclusively by the rear blades. There is then initiated a relative movement between the newly formed pleat and a sewing machine, such that the pleat is brought into position to be secured by sewing. Typically, the stitching includes at least a vertical stitch line, at the base of the pleat, and a horizontal stitch extending out to the front edge of the pleat. This allows the pleat folds to open and fan upwardly and outwardly from the L-shaped stitching. Frequently, it is desirable to include a second, short horizontal stitch partway between the base of the "L" and the top extremity of the fabric, such that the center accordion fold is at least lightly tacked and prevented from reversing and folding outward.
In general, the above described operations have been known and have been sought to be performed on an automatic or semiautomatic basis. Nevertheless, insofar as the applicant is aware, drapery manufacturing operations as practiced at the present time involve excessive amounts of hand labor, because of the substantial difficulties involved in more fully operating the manipulating and sewing operations required to be performed, in order to achieve a product of first class saleable quality.
Pursuant to one aspect of the invention, a novel, highly automated method and apparatus is provided for the production of pleated drapery fabrics, in which the production operations are substantially fully automated following the initial loading of the fabric onto an in-feed conveyor. In this respect, certain of the features of novelty reside in the conveyor itself, and include an improved arrangement for receiving, holding and conveying the stiffened upper edge margin of the fabric, which has been first properly folded by the operator before being loaded into the conveyor system.
Bearing in mind that successive pieces of fabric, although nominally of identical size, have measurable and sometimes significant variations in overall width, the arrangement of the invention provides for the automatic accommodation of and adjustment to such width variations. To this end, the in-feed conveyor includes a loading section having measuring calibrations at each end. When the operator loads a fabric section into the conveyor, he or she locates the fabric symmetrically with respect to the calibrations at each side, assuring that the fabric section is properly "centered" by the control facility. In addition, an edge guide may be brought over against the trailing edge, serving automatically to measure the width of the fabric and establish certain operating parameters related thereto. This arrangement enables the center pleat to be reliably centered on the fabric piece, regardless of width variations, and also enables a high degree of uniformity to be realized in the end runs of the fabric, by adjusting for width variations in the overall fabric. The latter control is achieved by incrementally varying the space between adjacent pleats sufficiently to accommodate in an unobtrusive way small variations in overall fabric width.
In accordance with another significant aspect of the invention, a series of pleating operations are effectively and efficiently carried out without manual intervention, by means of a novel and improved rotary drum-like device, having a plurality of pleat-forming stations which successively engage the fabric, effect the pleat formation in a partially known manner by the interweaving of pleatforming blades from opposite sides of the fabric, and then conveying the fabric via periodic rotational indexing motion of the drum-like device to a convenient position for effecting the sewing operation. In conjunction with a multiple position pleat-forming drum, there is provided an adjustable stroke fabric displacement element, engageable with the fabric in the area between a just-formed pleat and a pleat about to be formed. By extending the displacement element to the adjusted limit of its stroke, between pleat-forming operations, a predetermined length of fabric is displaced from a straight line path from one pleat-forming station to another, while the fabric is maintained under light tension. By this means, the length of fabric between pleats may be precisely and uniformly controlled, and accurately adjusted for various operating conditions, in order to achieve optimum symmetry in the finished article.
At the sewing position, the sewing machine and a related fabric clamping mechanism are used in a novel, cooperative arrangement to provide a pleat gripping and transport mechanism, engageable with the unsewn fabric pleat to withdraw it from the pleat-forming mechanism and transfer it to an appropriate location for completing the sewing operation. Among other things, the blades of the pleatforming device are slotted to receive the sewing machine needle and allow the needle to be withdrawn radially with respect to the pleat-forming drum. The sewing machine itself is controlled to be moved into engagement with the fabric, and the needle lowered to pass through the fabric, but not be retracted. With the newly formed pleat being engaged between the sewing plate and the fabric clamp, and the fabric also being positively engaged by the passed-through needle, the sewing machine and clamp can be synchronously withdrawn from the pleatforming drum, to effect release of the fabric therefrom and bring it, while being held in pleated condition by the clamp, to a more appropriate location for sewing.
As a specific but advantageous feature of the invention, a novel form of clamp is provided, which enables the fabric to be held in a generally fixed position for sewing, while the sewing machine itself and the sewing plate supporting the fabric, are moved through the necessary excursions to effect the desired L-shaped or F-shaped tack stitch. To this end, the clamp is mounted to accommodate a limited, one stitch length movement in any direction, so that the fabric and clamp may move along with the constantly laterally moving sewing needle during the times when the needle has penetrated the fabric. When the needle is withdrawn, the fabric and clamp return to their "normal" positions in preparation for execution of the next stitch. This arrangement enables the stitching operation to be performed at extremely high speeds, without unduly stressing the needle or the fabric.
Another particularly advantageous feature of the present invention resides in a novel arrangement of indexing a pleat-forming element, in the specific example a rotary drum, which functions with additional, selectively operable fold-forming blades projectable from the front side of the fabric, to shape and form the end runs of the fabric, to enable the end runs to be properly and efficiently tacked by the sewing machine both prior to the sewing of the first pleat and following the sewing of the last pleat, all without the necessity of operator intervention.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment and to the accompanying drawings. It will be particularly understood that the variods described features of the invention may in many cases be utilized independently of one another, and it should not be assumed that any or all of the inventive features need be utilized in combination, except as otherwise set forth in the hereinafter appended claims.